Means for applying a trimming condenser to a main condenser



June 4, 1935. E. D. KOEPPING MEANS FOR APPLYING A TRIMMING CONDENSER TO A MAIN CONDENSER Filed May 7, 1931 FIG! FIG. 3

gmventoz EM/L D. KUEPP/NG 6111014401 Patented June 4, 1935 PATENT OFFICE MEANS roa APPLYING A TRIMMING CON- DENSER TO A MAIN CONDENSER Emil Dudley Koepping, Haddon Heights, N. J.,

assignor to Radio Condenser Company, Camden, N. J.

Application May 7, 1931, Serial No. 535,592

7 Claims.

This invention relates to the construction of variable condensers used in radio receiving sets, although it may have other uses.

In my application, S. N. 469,033, filed July 19,

1930, I have shown and described a construction of a condenser which may be built up by thecondenser manufacturer, tested or calibrated, and placed in stock ready for shipment against orders received by the radio set manufacturer. The

specifications of the different set manufacturers vary as to the characteristics of the condensers required in their respective tunable circuitssome desire what is referred to in the trade as a trimming condenser by which the initial minimum capacity of the condenser can be adjusted, while others do not require or ask for the tuning condensers to be equipped with trimmers.

In certain designs of receiving sets, the space may be very limited, and consequently the design of the tuning condenser must be very compact,

.and it is the principal object of my invention to provide a construction by which a trimming condensermay be applied to a condenser that has already been made, calibrated, and stocked, without changing or throwing out the calibration of the main condenser by the addition of the trimmer.

Stated in another way, it is the object of my present invention to attain the advantages set forth in my application herein identified, when applying the principles to a compact design of condenser. limitation, I have shown my improvement applied to a two-gang condenser, but it is to be understood that the invention may be applied to any number of units which may be arranged in gang form for single control. Of course, the invention may be applied to a single unit condenser if so desired.

In the drawing:

Figure 1 illustrates a side elevation of a twounit gang condenser with the rotor moved slightly out of its maximum capacity position, and showing the trimmer condenser removed from one of the units. I

Figure 2 is a view on the line 2-2 of Figure 1.

Figure 3 is a plan view of the special bracket for mounting the trimmer condenser.

Figure 4 is a section on the line 4-4 of Figure 3.

In the drawing, I is a frame having end support plates 2 and 3 which carry a shaft 4 supported by anti-friction bearing members carried in the races 5 and 6, substantially in the same manner as shown and described in Cramer Patent 1,800,719, issued April 14,1931. On the shaft By way of illustration, but not of 4, are mounted in any satisfactory manner, a pair of sleeves I which support a plurality of rotor plates 8, the ends of which are preferably fastened together by tie bars 9. Each stator group of plates I0 is supported by tie bars II which are 5 clamped, by means of the clamping bar I2 and screws 13, to one end of an insulator I 4. The other end of the insulator I4 is fastened in any suitable manner as by rivets IE, to a lug I5 thrown upwardly from the side of the frame I.

As shown in Figure 1, the insulators I 4 are positioned in openings I! which are punched in the frame I preferably at the time the lugs I5 are formed. It is to be understood that both sides of each of the stator units are fastened to the frame I in the manner just described.

In the construction shown, it is to be noted that the insulator I4 is relatively narrow and there is not room between the screws I3 and the rivets IE to properly mount a trimming condenser on the insulator I4. Besides, as has been pointed out, the screws I3 should not be disturbed after the stator has been fastened in its working position and the condenser has been calibrated to its rated capacity. Therefore, some special means must be provided for mounting the trimming condenser on one or both sides of each of the condenser units.

In order to accomplish this, I have provided a bracket I 8 having holes I 9 therein through which the screws I3 pass, thereby clamping the bracket I8 securely under the heads of the screws I3. The bracket therefore also serves as a washer for the heads of the screws l3. As will be noticed in Figures 2, 3 and 4, the bracket I8 is provided with an offset and the lower portion thereof is provided with a pair of upturned side lugs 20, and between these side lugs, the extended part 2I of the trimmer plate 22 is positioned. These lugs prevent the trimmer plate from turning or moving later- 0 ally when the screw 23, which is adapted to fit the tapped hole 24, is tightened to fasten the plate on the bracket. Also, when the screw 26 is moved to adjust the cap of the trimmer condenser, the movement of the screw tends to weave the plate 21 on the bracket, and the side lugs 20 prevent this weaving action and make possible a smooth adjustment of capacity. The trimmer condenser plate 22 overlaps the frame I and is kept from contacting with the frame I by a suitable insulator 25, preferably of mica, which is held in position by two lugs 28 and an adjusting screw 26 that passes through a bushing 21 of insulating material.

The trimmer condenser 22, including its extension 2 I, is so formed that there is a spring tension always acting outwardly away from the frame I, so that as the screw 26 is backed away from the plate I, the trimmer plate 22 will follow the screw,

and of course when the screw is turned inwardly the plate 22 is of course nearer the plate I, thereby slightly changing the capacity of the main condenser unit, it being understood that the screws I3 which are fastened to the bracket I8 through the insulator I4, connect each stator group with the trimmer condenser plate 22.

The extension 2| of the plate 22 is provided with an orifice 29 to receive a conductor which is soldered to said extension, thereby completing a connection from the condenser to the trimmer plate, as well as the stator of the main condenser. When the trimmer plate 22 is not used, the conductor for the stator circuit may be connected directly to the bracket I8 by use of the screw 23 and suitable washers, or a small terminal may be used, one end being clamped to the bracket I8 by screw 23, while the conductor is soldered to its opposite end. If it is desired at a later time to add the trimmer plate, the conductor can be readily transferred from the bracket or terminal, as above set forth, to the plate after mounting it on the bracket.

Since the condenser is assembled with the bracket I8, which is a relatively inexpensive piece, when the condenser is originally assembled, it will be seen that the trimmer condenser 22 may be applied to the bracket I8 in the manner described without affecting the original setting of the main condenser, and consequently, its original calibration is not disturbed.

Having thus described my invention, what I claim is: Y

1. In an electrical condenser having a frame and relatively fixed and movable sets of elements carried thereby, one set being fastened to at least two insulators carried by the frame, a bracket permanently attached to at least one of the insulators by said one set fastening means, a trimmer condenser plate adapted to be mounted on said bracket, and means for adjusting the capacity position of said plate with respect to the frame.

2. A main condenser having a frame, stator and rotor groups of plates, said stator group of plates being held together by a plurality of means fastened to insulators carried by the frame, at least one of said insulators having a bracket fas- 'and overlying a part of, the frame, and means for adjusting the capacity position of said plate with respect to the frame.

3. Quick attachment means for applying a trimming condenser to a main condenser having its stator fastened to insulators supported on a frame, comprising a bracket held to one of said insulators by the stator fastening means, a plate adapted to be mounted on the bracket so as to extend over a part of the frame, and means carried by the frame for adjusting the position of said plate with respect to the frame.

4. In a compact type of main condenser having a frame and fixed and movable groups of plates carried by the frame, said fixed groups of plates having mounting means fastened to one end of relatively narrow insulators attached to the frame at their opposite ends; means for applying a trimming condenser to the main condenser consisting of, a bracket held to at least one of the insulators by a part of said stator mounting means, aplate adapted to be fastened to the bracket and extending over a part of the frame, means for preventing the plate from coming into direct contact with the frame, and means for adjusting its position with respect to the frame.

5. In an electrical condenser as set forth in claim 1, further characterized in that the bracket has a pair of upturned side lugs between which a part of said condenser plate is positioned, whereby the plate is prevented from rotating or shifting laterally on the bracket.

6. A compact type of condenser as set forth in claim 4, further characterized in that the bracket is provided with means for preventing the trimmer condenser plate from shifting on the bracket when it is being fastened in position.

7. An electrical condenser having a frame, stator and rotor groups of plates carried by the frame, said stator group of plates being mounted on insulators fastened to the frame, a bracket carried by at least one of said insulators and electrically connected to the stator group of plates, a trimmer plate adapted to be fastened to the bracket and having a part extending over a part of the frame but out of contact therewith, and means for adjusting the capacity position of said trimmer plate with respect to the frame.

EMIL DUDLEY KOEPPING. 

